Add metadata to logger

[teamon]

wip, testing in progress

[teamon]

@yordis wdyt of this as an idea?

[yordis]

Overall, I like the idea, the only feedback is about documentation.

We should document in one place all the "reserved" options that have a given intent.

I like it!

[yordis]

Recently, I had to send the data somehow, I ended up doing the following:

defmodule Umbrella.Tesla.Logger do
  def log_level(%Tesla.Env{status: status}) when status in 400..499, do: :warning
  def log_level(_env), do: :default

  def log_formatter(req, {:error, reason}, time) do
    %{
      time: time,
      method: upper_case_method(req),
      url: req.url,
      path: req.opts[:req_url],
      req_body: log_env_body(req),
      reason: inspect(reason)
    }
  end

  def log_formatter(req, {:ok, resp}, time) do
    %{
      time: time,
      status: resp.status,
      method: upper_case_method(req),
      url: req.url,
      path: req.opts[:req_url],
      req_body: log_env_body(req),
      resp_body: log_env_body(resp)
    }
  end

  defp log_env_body(%Tesla.Env{status: status} = env) when status >= 400 do
    inspect(env.body)
  end

  defp log_env_body(_), do: "[REDACTED]"

  defp upper_case_method(%Tesla.Env{} = env) do
    env.method
    |> to_string()
    |> String.upcase()
  end
end

As long as the metadata is under a given key tesla: [....] I do not see any issue, although, I still believe that structured logging is much better.

Being said, the ultimate way to deal with this is to simple allow the user to do Logger calls themselves and give them enough information to know what to do with it.

I think it was a misdirection to call Logger ourselves. Except for the debug flag!

[yordis]

@teamon do you mind rebasing? I am still unsure about the feature and the final version